FI69116C - UPPLOESNING AV MINERALER VID HOEG TEMPERATURE MEDELST VAETSKA INNEHAOLLANDE SOM HUVUDKONPONENT LOESLIG BIKARBONAT - Google Patents

Description

rn «« ADVERTISING PUBLICATION

fBl (11) utlAggningsskrift 69116 e ~ p \ § c (45) -: · ':: 1- 1 ^ 55 V ^ (51) Kv.lk.4 / lnt.Ci.4 C 22 B 60/02, 3 ** / 22, 3 ** / 3 * »(21) Patent application - Patentansfiknlng 790375 (22) Application date— Ansöknlngsdag 05-02.79 (23) Starting date— Glltighetsdag 05-02.79 (41) Published public - Blivlt offentlig 1 0.08. 79

National Board of Patents and Registration Date of display and hearing. - O0 Qg gc

Patent and registration authorities' 'Ansökan utlagd och utl.skriften publlcerad *' 3 (32) (33) (31) Privilege claimed - Begärd priorltet 09.02.78 France-France (FR) 780 * + ** 68 (71) Aluminum Pechiney , 28 rue de Bonnel, F-69003 Lyon, France-France (FR) (72) Pierre Maural, Aix-en-Provence, Francois Nicolas, Aix-en-Provence,

Bernard Bosca, Gardanne, France-France (FR) (7 * 0 Berggren Oy Ab (5 * 0 High-temperature dissolution of minerals by means of a liquid containing soluble bicarbonate as the main constituent) - Upper extraction of minerals at high temperatures in the presence of other components

The present invention relates to a novel process for oxidatively dissolving at high temperature minerals containing uranium, vanadium or molybdenum in an aqueous liquid containing sodium bicarbonate and sodium carbonate, comprising free oxygen which is blown into the reaction medium and separated from the waste rock and liquid containing dissolved metal or metals.

Methods are already known in which minerals such as uranium-containing minerals are dissolved by oxidation in temporal carbonate solutions which also contain a small amount of sodium bicarbonate. This dissolution took place in the presence of free oxygen, which was blown into the hot reaction solution.

The procedures used to carry out this oxidative alkaline dissolution are described in the literature on the subject. (The Extrative Metallurgy of Uranium, Robert C. Merrit, edited by the Colorado School of Mines Research Institute, printed 1971, page 83 onwards).

69116

According to the first procedure, a uranium-containing mineral, most preferably one with a high carbonate content, was dissolved with a liquid containing 40-50 g / l Na 2 CO 3 and 10-20 g / l NaHCO 3 and accompanied by oxygen or iLma, which was blown into the reaction mixture.

The dissolution took place in an autoclave and the temperature was between 95-120 ° C and the total pressure in the reaction chamber was between 2-6.5 bar and the dissolution time was 4-20 h.

According to another method, the same uranium-containing mineral rich in carbonates was dissolved in the same liquid containing 40-50 g / l Na 2 CO 3 and 10-20 g / l NaHCO 3 and oxygen or air was blown into the reaction solution of the mineral. But the reaction conditions in "Pachuca" were different: the temperature was between 75-80 ° C, while the pressure of the air or oxygen blown into the reaction mixture was between 2-3 bar and the dissolution time was 96 h.

According to the author of the report, these procedures have proven to be advantageous in the dissolution of certain uranium-containing minerals, but they are difficult to apply in the case of refractory or silicon-containing minerals.

In addition, these procedures require high, very long reactor residence times to achieve high uranium dissolution rates.

Due to these disadvantages, the applicant has continued research and developed a new method for oxidatively dissolving minerals containing at least one metal belonging to the group of uranium, vanadium and molybdenum, which can improve the reaction kinetics and the extraction yields of the desired metal or metals. to treat minerals of very variable composition, in particular those rich in carbonates, those in which the metal or metals are combined with organic substances and those which have hitherto been obtained by those skilled in the art by dissolving in an acidic medium.

In the new process according to the invention, minerals containing uranium, vanadium and molybdenum are oxidatively dissolved at high temperature and pressure in an aqueous liquid containing sodium carbonate and sodium bicarbonate and free oxygen is blown into the reaction medium, and the waste rock is separated and the waste rock is separated. containing dissolved metal or metals, the process being characterized in that the mineral is treated with an aqueous liquid containing most of the sodium bicarbonate and less of the sodium carbonate so that the mass ratio of NaHCO 2 / Na 2 CO 2 is at least 1.5 and free oxygen is blown into the reaction medium so that the partial pressure of oxygen in the reactor is between 0.1 and 20 bar and that the temperature of the reaction medium is maintained between 160 and 300 ° C and for a maximum of 6 hours.

As is known, the oxidative dissolution of the above minerals takes place by blowing free oxygen, either in the form of an oxygen-containing gas such as air, in the form of oxygen-enriched air or in the form of oxygen alone, this pressure being carried out at a pressure of preferably 5-15 bar. .

As already mentioned, the aqueous dissolution liquid consists of a larger part of sodium bicarbonate and a smaller part of sodium? carbonate so that the mass ratio of NaHCO 3 / Na 2 CO 2 is at least 1.5.

The patent applicant has found that it is advantageous to select a ratio with limit values of 4 and 80.

Depending on the nature of the mineral, said ratio is determined by the desired value, and the concentration of the liquid to be dissolved may vary within wide limits for each of the reactants present. Thus, for example, the concentration of NaHCO 3 may vary between 10 g / l

300 g / l, but is most preferably between 80 g / l and 160 g / l, while the concentration of Na 2 CO 2 may be between 0 g / 1 and 50 g / l, but is

most preferably between 0 g / 1-30 g / l. j

According to a variant which has proved advantageous within the scope of the process according to the invention, CO 2 gas can be blown into the reaction medium during dissolution. This blowing can take place continuously or intermittently, with the flow being either constant or variable.

CO 2 gas blowing can be used to control and at the same time regulate the CO 2 HT concentration of the reaction medium, which can vary because the amount of oxygen blown in can be greater than what is actually required for oxidation.

4 69116 ~

The temperature ranges used in the dissolution have been specifically studied by the applicant. He has been able to define a particularly preferred temperature range between the limit values of 160 ° C and 300 ° C. But in most cases, the dissolution temperature may preferably be between 170-220 ° C.

The dissolution time is usually short and does not exceed 6 h; it is most preferably 1/2 to 2 h.

According to a special design, it may be advantageous, in the case of some minerals, to add a conventional oxidation catalyst to the reaction medium, which can be used to improve the dissolution kinetics.

In practice, the process according to the invention may also be preceded by one or more treatments of the mineral before its actual dissolution takes place under the conditions described above. First and foremost, not only conventional mineral grinding may be necessary, but particularly efficient grinding to multiply the contact points between the mineral granules and the dissolution liquid. In addition, it may be advantageous to remove the organic matter contained in the mineral in advance by annealing at a controlled temperature.

Further treatment of the mineral with lime milk, soda solution, soda lime liquid, liquid containing CO 2 and / or CO 2 H ions attached to at least one cation such as Na +, K +, NH 2, Ca 2+ may be considered. In addition, in some cases it may still be advantageous to carry out the physical enrichment in advance by a method known to those skilled in the art, such as by flotation.

Of course, different pretreatments can be combined.

The advantages of the method according to the invention will become more apparent with the aid of illustrative examples.

Example 1:

The method according to the invention was used to treat a uranium-containing mineral, the aggregation of which in parts by weight is as follows:

II

5,691 1 6 U 0.064%

SiO 2 68.4% Al 2 O 3 14.5%

Fe 2 O 3 4.3%

MgO 1.35%

CaO 0.70%

Na 2 O 0.70% K 2 O 1.65%

TiO 2 0.75% P2 ° 5 0.18 * other 4.656% (of which CO 2 2.0%, and organic C 0.37%) 1000 kg of this mineral were ground so that the grain size was less than 200 μl and placed then into an autoclave together with 1051 kg of a dissolution liquid containing 158 kg of NaHCO 3 and 30 kg of Fe (OH) 3 as oxidation catalyst.

The reaction medium was kept at 200 ° C for 2 h.

Throughout the dissolution, oxygen was blown into the reaction medium at a flow rate of about 3 m 2 / h and a total pressure in the reactor of 23 bar.

After this time, the autoclave was cooled and degassed.

The resulting reaction solution was filtered and washed with water.

In this way, 725 l of mother liquor and 1200 l of washing solution were obtained. The composition of the recovered mother liquor was as follows:

Na 2 CO 3 26.5 g / l

NaHCO 3 113.5 g / l

Uranium 0.58 g / l (expressed as U)

Na 2 CO 3 6.07 g / l

NaKCO 3 26 g / l U 0.133 g / l

The composition of the precipitated solid wash was as follows:

The precipitated solid fraction had a uranium content of 68 ppm, corresponding to a uranium yield of 89.4%.

69116

Example 2: A uranium-containing mineral containing only a small amount of uranium and having the following composition in parts by weight was treated:

Uranium 0.039%

SiO2 70.6% Al2O3 15.8%

Fe 2 O 3 3.4%

MgO 0.90%

CaO 0.15%

Na 2 O 2.20% K 2 O 3.45%

TiCl 2 0.45% P 2 O 5 0.09%

The other 2.901% (of which CO2 0.70% and organic C 0.18% r 750 kg of this mineral was ground so that the grain size was less than 200 yU was then placed in an autoclave together with 787 kg of a dissolution liquid containing 158 kg of NaHCO -j and 20 kg Fe (OH) 3 as a catalyst.

The temperature of the reaction medium was maintained at 200 ° C for 2 h, during which time oxygen was blown at a flow rate of 2.5 m 3 / h and the total pressure was 23 bar.

When the reaction solution was filtered, 500 l of mother liquor and 1000 l of washing liquid were obtained.

The composition of the recovered mother liquor was as follows:

Na 2 CO 3 41.12 g / l

NaHCO 3 90.6 g / l U 0.345 g / l

Na 2 CO 3 10.28 g / l

NaHCO 3 22.65 g / l U 0.086 g / l

The composition of the precipitated solid fraction washing liquid was as follows: 11,691 1 6 7

The solid fraction obtained contained 5 ppm of uranium, which corresponded to 87.3% of the uranium yield.

Example 3:

The method according to the invention was used to treat a uranium-containing mineral which was highly carbonate and which, after drying, had the following composition in weight ratios: U 0.122%

SiO2 50.0%

Al 2 O 3 9.8%

Fe 2 O 3 4.2%

MgO 3.6%

CaO 10.4%

Na 2 O 4.5% K 2 O 0.20%

TiCl 2 0.40% P 2 O 5 0.058% V 2 O 5 0.008%

Mo 0.01% S 0.14%

An additional 16.562% (of which COo 13.83% and organic C 0.205%) 600 kg of this dry mineral was ground to a grain size of 160 yU and then placed in an autoclave together with 630 kg of a dissolution liquid containing 96 kg of NaHCO 3 and 18 kg of Fe (OH ) 3 as an oxidation catalyst.

The autoclave was heated so that the reaction medium was 180 degrees and the same oxygen was blown at a flow rate of 2 mVh, causing effervescence in the pulp. During the oxidative dissolution, the total pressure in the autoclave was 15 bar.

After 2 h, the autoclave was cooled and degassed.

The resulting reaction solution was filtered and washed with water.

In this way, 565 L of mother liquor and 905 L of liquid from the washing of the solid fraction were recovered.

The composition of the recovered mother liquor was as follows: 3 6911 6

Na 2 CO 3 28.5 g / l

NaHCC> 3 108.7 g / l uranium 1.1 g / l (expressed as U)

Na 2 SO 4 1.28 g / l

The composition of the precipitated solid wash was as follows:

Na 2 CO 3 2.05 g / l

NaHCO 3 7.80 g / l U 0.08 g / l

Na 2 SO 4 0.09 g / l

The recovered solid fraction contained 58 ppm uranium, corresponding to 95.2% uranium yield.

Example 4;

The same mineral treated in Example 3 was dissolved under the same conditions, but without the oxidizing catalyst.

The temperature, dissolution time, oxygen flow rate and reactor pressure were the same as in Example 3.

Without any oxidation catalyst, the recovered solid fraction had a uranium content of 60 ppm, corresponding to a uranium yield of 95.1%.

Example 5: A mineral containing both uranium and molybdenum and having the following composition in parts by weight after drying was treated by the process according to the invention: U 0.255%

Mo 0.054%

SiO2 62.3%

Al 2 O 3 13.5%

Fe2C> 3 4.1%

MgO 0.34%

CaO 0.59%

Na 2 O 7,19% K 2 O 0,47% T 1 O 2 0,46% P 2 O 5 0,07% v 2 O 5 0,01% S 0,1% li 69116

The remaining 10/561% (of which CC> 2 0.85% and organic C 0.108%) 750 kg of this mineral was ground to a grain size of 160 and then placed in an autoclave together with 787 kg of a dissolution liquid containing 150 g / l NaHCO and 22 kg of Fe (OH) 3 as oxidation catalyst.

The autoclave was heated so that the reaction medium was at 180 ° C while blowing oxygen at a flow rate of 2.5 m / h, which caused bubbling in the mass. During the oxidative dissolution, the total pressure in the autoclave was 15 bar.

After 2 h, the autoclave was cooled and degassed.

The resulting reaction solution was filtered and washed with water.

The following was recovered: 568 l of mother liquor and 800 l of liquid from the washing of the solid fraction.

The composition of the recovered mother liquor was as follows:

Na 2 CO 3 27.5 g / l

NaHCO 3 109.8 g / l uranium 2.37 g / l (expressed as U)

Mo 0.195 g / l

Na 2 SO 4 2.2 g / l

The composition of the precipitated solid wash was as follows:

Na 2 CO 3 6.2 g / l

NaHCO 3 24.9 g / l U 0.54 g / l

Mo 0.04 g / l

Na 2 SO 4 0.5 g / l

The solid fraction obtained had a uranium content of 64 ppm, which corresponded to a uranium yield of 97.5%.

Example 6:

Dissolution of the Sara mineral treated in Example 5 but without an oxidation catalyst was performed.

The temperature, dissolution time, oxygen flow rate, and reactor pressure 10 691 1 6 were the same as in Example 5, as were the amounts of mineral and dissolution fluid used.

Without any oxidation catalyst, the recovered solid fraction had a uranium content of 77 ppm, corresponding to a yield of 97.0%.

Example 7 The same mineral mentioned in Example 5 containing uranium and molybdenum was treated according to the process of the invention.

750 kg of this dry mineral was ground to a grain size of 160 yU, and then placed in an autoclave together with 787 kg of dissolution liquid containing 135 g / l NaHCO 3 and 15 g / l Na 2 CO 3. The autoclave was heated so that the reaction medium was at 180 ° C and the same oxygen was blown at a flow rate of 2.5 m 2 / h, causing pulping in the pulp.

During the oxidative dissolution, the pressure in the autoclave was 15.5 bar.

After 1 h, the autoclave was cooled and degassed. The resulting solution was filtered and washed with water.

In this way: 562 l of mother liquor and 800 l of liquid from the washing of the solid fraction were obtained.

The resulting mother liquor had the following composition:

Na 2 CO 3 28.2 g / l

NaHCO 3 109.2 g / l uranium 2.46 g / l (expressed as U) MO 0.20 g / l

Na 2 SO 4 2.1 g / l

The composition of the precipitated solid wash was as follows:

II

Claims (7)

A process for high temperature oxidizing solution of ore, containing uranium, vanadium and molybdenum, by an aqueous solution containing sodium bicarbonate and sodium carbonate, in the presence of free oxygen, is injected into the reaction medium, the separation from unwanted rock and the resulting effect the solution contains the metal (s) loaded, characterized in that the ore is treated with an aqueous solution containing to a greater part sodium bicarbonate and to a minor part sodium carbonate in such a way that the mass ratio of sodium uricarbonate / sodium carbonate is at least equal to 1.5; free oxygen is injected into the reaction medium in such a way that the partial pressure of the oxygen in the reactor is in the range 0.1 to 20 bar, and that the temperature of the reaction medium is maintained between 160 ° C and 300 ° C for a period of not more than 6 hours. Process according to Claim 1, characterized in that the mass ratio of sodium bicarbonate / sodium carbonate is between 4 and 80. Process according to claim 1, characterized in that the partial pressure of oxygen in the reactor is preferably in the range 5 to 15 bar. 4. A process according to claim 1, characterized in that the temperature of the reaction medium is preferably maintained between 180 ° C and 220 ° C. Process according to claim 1, characterized in that the concentration of NaHCO 3 in the attack solution can vary between 10 g / l and 300 g / l, preferably between 80 g / l and 160 g / l, while the concentration of g / l and 50 g / l, but preferably between 0 g / l and 30 g / l. li